Most homes in modern societies have multiple telephone sets sharing one telephone number provided by a fixed line Public Switched Telephone Network (PSTN) or broadband Voice Over Internet Protocol (VoIP) network operator. Over the last few years, the use of fixed line home phones has been greatly reduced as the popularity of mobile telephones has increased. However, many households still retain their fixed line home telephones for various reasons. One such reason is that family members can share a common phone number and talk to the same external caller at the same time. Current mobile phone service providers are unable to provide a comparable function unless family members invoke a multiple party call procedure from each of the family member's mobile phones.
Many families and groups today have multiple cellular devices having different telephone numbers that are incorporated into a single billing plan. For example, a family plan may include three or more telephone numbers assigned to different cellular devices with a fixed number of minutes allocated on a monthly basis for all members of the plan. The telephone numbers assigned to the family plan may be linked in a database for billing purposes. However, as noted above, a multiparty, (e.g. greater than two), call with other family members using a cellular device requires one or more parties to a call to invoke a multiple call procedure using special software and/or hardware in the cellular device.
By way of background, typical call processing functions can be found in IETF RFC 2543, Session Initiation Protocol (SIP). Telephony equipment implementing call processing functions may include a Mobile Switch Center (MSC) in the cellular network, a Class 5 Switch in the Public Switched Telephone Network (PSTN) and a SIP server in the wireless or fixed line Internet Protocol (IP) network.